Phenacyl thiocyanate: crystal structure, conformational features and herbicide safening effects of the condensation product with isatin

Abstract

Phenacyl bromide interacted with potassium thiocyanate in acetone to form phenacyl thiocyanate (1), the structure of which was studied in detail by X-ray diffraction analysis. X-ray analysis was performed on a Bruker D8 Quest diffractometer (MoKα radiation, λ = 0.71073 Å, graphite monochromator) at 293.15 K. The X-ray diffraction data: [(1) C9H7NOS, M = 177.22; monoclinic system, space group Р21/c; crystal size 0.59 × 0.29 × 0.18 mm; cell parameters: a = 10.922(19) Å, b = 5.600(8) Å, c = 15.18(2) Å; β = 105.62(5), V = 894(2) Å3, Z = 4; calc = 1.316 g/cm3;  = 0.310 mm–1; F(000) = 368.0; collection area for 2q : 7.6–41.2; –10 ≤ h ≤ 10, –5 ≤ k ≤ 5, –14 ≤ l ≤ 15; total reflections 5869; independent reflections 909 (Rint = 0.0593); GOOF = 1.047; R-factor = 0.0657]. Quantum-chemical studies of the molecular geometry and vibrational spectrum of phenacyl thiocyanate (1) were performed with ORCA 6.0.1 software package using the hybrid DFT functional B3LYP with dispersion correction D4 with split valence basis set def2-TZVP. The most stable conformers of phenacyl thiocyanate (1) have been found, and the experimental and calculated IR spectra have been compared. Triethylammonium 2-oxo-1-(2-oxoindolin-3-ylidene)-2-phenylethane-1-thiolate (2), prepared by the reaction of phenacyl thiocyanate 1 with isatin in the presence of triethylaminem has shown a moderate herbicide safening effect against 2,4-D herbicide in the laboratory experiment on cv. Master sunflower seedlings.